Monday, July 02, 2007

"Edge of Evolution" - a cure for malaria?

One of the interesting aspects that can be drawn from Behe's book is that, if life requires intelligent design, it should be possible to devise a cure for malaria. Conversely, if a cure for malaria can be found along the lines that Behe suggests (not any old cure), this would be evidence in support of an ID perspective.

How so?

Behe argues that for most new anti-malarial drugs, a single specific mutation in the malaria parasite genome is sufficient to convey resistance to the drug in the organism. Because of the number of parasite cells reproducing in a human, it is fairly likely that this resistance would naturally arise quite quickly - and indeed, it has been shown, he argues, that most new anti-malarials have limited long-term value.

By far the most successful anti-malarial drug is chloroquine. He argues that the reason for this is that for a parasite to be resistant to this drug, it requires two mutations. A single mutation in any given parasite is improbable - but with large numbers of parasites per person, it is likely that resistance will not take long to arise. For an organism to undergo two mutations, both of which are required to provide resistance, is much less probable - and the number of occasions around the world where chloroquine resistance has developed in a parasite is very few. I think Behe says that the mutations don't have to be simultaneous, but they do have to both be present - and this is not likely to happen - I apologise if I am misrepresenting his argument.

So, Behe argues, the way to beat malaria is to provide a drug that the parasite would only be able to have resistance to with four mutations in the genome. The probability of any parasite having all four mutations would be exceedingly small.

Given the state of the art in devising anti-malarials, it strikes me that this would in any case be a sensible long-term aim for drug development. However, Behe argues, whereas darwinism holds no hope - random mutations will achieve anything in the end, darwinism argues (despite the obvious fact that chloroquine requiring two mutations has been measurably more successful than other drugs requiring one) - his presentation, which argues that such developments are outside "the edge of evolution" is more optimistic - it suggests that malaria could be defeated.